A CAD-4 SDP-34M time-sharing X-ray diffractometer system will be acquired to replace an ancient Picker diffractometer used for protein crystal diffraction data collection and an eight year old Data General mini-computer, for which the maintenance costs have become excessive. An existing CAD-4 diffractometer, used for lipid and carbohydrate research, will be linked to this system by means of a microprocessor, and its performance will be enhanced with a new detector system and modern software control.